| 401 | O G & E | Oklahoma City, OK 73124 | Oil & Gas Operator | Feb 2014 |
| 402 | O K Swabbing Inc | Hennessey, OK 73742 | Oil & Gas Operator | Apr 2026 |
| 403 | O'Neill Properties, LTD. | Midland, TX 79702 | Oil & Gas Operator | Jul 2026 |
| 404 | Oak Resources Inc | Tulsa, OK 74153 | Oil & Gas Operator | Aug 2013 |
| 405 | Oil Producers, Inc. Of Kansas | Wichita, KS 67206 | Oil & Gas Operator | Jul 2026 |
| 406 | Oilsearch Corporation | Albuquerque, NM 87109 | Oil & Gas Operator | Feb 1994 |
| 407 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2026 |
| 408 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Apr 2026 |
| 409 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | May 2026 |
| 410 | Old Dominion Oil Corporation | Oklahoma City, OK 73107 | Oil & Gas Operator | Apr 2009 |
| 411 | Olympia Oil Inc | Edmond, OK 73083-7088 | Oil & Gas Operator | Jul 2020 |
| 412 | Omimex International Corp | Fort Worth, TX 76103-2300 | Oil & Gas Operator | Apr 2026 |
| 413 | Oneok Exploration Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 414 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 415 | Onshore Royalties LLC | Houston, TX 77269 | Oil & Gas Operator | May 2026 |
| 416 | Onyx Properties Corp | Oklahoma City, OK 73114 | Oil & Gas Operator | May 2006 |
| 417 | Opubco Resources Of TX Inc | Dallas, TX 75231 | Oil & Gas Operator | Sep 2005 |
| 418 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 419 | Overflow Energy, LLC | Perryton, TX 79070 | Oil & Gas Operator | Jul 2026 |
| 420 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | May 2026 |
| 421 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Jul 2026 |
| 422 | Pace Petroleum Company | Dallas, TX 75206 | Oil & Gas Operator | Jul 2026 |
| 423 | Pacific Enterprise Oil Co USA | Los Angeles, CA 90071-2005 | Oil & Gas Operator | Aug 2012 |
| 424 | Pacific Enterprises Royalty Co | Oklahoma City, OK 73101 | Oil & Gas Operator | Feb 2002 |
| 425 | Pal Kids Inc | Coronado, CA 92118 | Oil & Gas Operator | Nov 2000 |
| 426 | Palace Exploration Company | Houston, TX 77002 | Oil & Gas Operator | Mar 2007 |
| 427 | Paleo, Inc. | Oklahoma City, OK 73112 | Oil & Gas Operator | Jul 2026 |
| 428 | Panada Exploration, Inc. | Tulsa, OK 74135 | Oil & Gas Operator | Jun 1996 |
| 429 | Panhandle Eastern Pipeline Company LP | Houston, TX 77002-6803 | Oil & Gas Operator | Oct 1999 |
| 430 | Panhandle Oil & Gas Consultants Inc | Woodward, OK 73802-5011 | Oil & Gas Operator | Jul 2015 |
| 431 | Pantera Energy Company | Amarillo, TX 79101 | Oil & Gas Operator | Jul 2026 |
| 432 | Panther Energy Company, LLC | Tulsa, OK 74103 | Oil & Gas Operator | May 2022 |
| 433 | Panther Operating LLC | Pauls Valley, OK 73075 | Oil & Gas Operator | Apr 2026 |
| 434 | Pardee Production Co. | Skiatook, OK 74070 | Oil & Gas Operator | Mar 2021 |
| 435 | Parwest Land Exploration Inc | Oklahoma City, OK 73112 | Oil & Gas Operator | Apr 2026 |
| 436 | Patina Oil & Gas Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2016 |
| 437 | Patina Oklahoma Corp | Duncan, OK 73533-9523 | Oil & Gas Operator | Nov 2014 |
| 438 | Payne Exploration Company | Crescent, OK 73028 | Oil & Gas Operator | Apr 2026 |
| 439 | Payne W C Family Trust | Oklahoma City, OK 73116-9044 | Oil & Gas Operator | Mar 2015 |
| 440 | Pearl Oil Company | Nichols Hills, OK 73120-1408 | Oil & Gas Operator | Nov 2023 |
| 441 | Pelican Production Company | New Orleans, LA 70130-2477 | Oil & Gas Operator | Mar 2014 |
| 442 | Pengo Petroleum Inc | | Oil & Gas Operator | Dec 2013 |
| 443 | Pennant Oil & Gas LLC | Oklahma City, OK 73159-6905 | Oil & Gas Operator | Jan 2024 |
| 444 | Penntex Resources, L.P. | State College, PA 16803 | Oil & Gas Operator | Mar 2016 |
| 445 | Peregrine Petroleum Corp | Oklahoma City, OK 73116-7639 | Oil & Gas Operator | May 2020 |
| 446 | Pet-Ex Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2026 |
| 447 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 448 | Petro-Management Assoc., Inc. | Edmond, OK 73083-2346 | Oil & Gas Operator | Jun 2007 |
| 449 | Petrocorp Incorporated | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2021 |
| 450 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 451 | Petroleum Development Company | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2026 |
| 452 | Petroleum Investment Inc | Oklahoma City, OK 73118 | Oil & Gas Operator | Nov 1998 |
| 453 | Petroleum Properties MGMT. Co. | Oklahoma City, OK 73118 | Oil & Gas Operator | Dec 2014 |
| 454 | Pitco Production Company | Tulsa, OK 74170-2320 | Oil & Gas Operator | May 2013 |
| 455 | Plains Resources Inc. | Houston, TX 77002 | Oil & Gas Operator | Jul 2008 |
| 456 | Plano Petroleum LLC | Plano, TX 75093-8773 | Oil & Gas Operator | Apr 2013 |
| 457 | Polaris Energy Dev Co | Tulsa, OK 74135 | Oil & Gas Operator | Apr 2000 |
| 458 | Pollok Energy LLC | Tulsa, OK 74159 | Oil & Gas Operator | May 2026 |
| 459 | Portfolio Oil Corporation | Oklahoma City, OK 73119 | Oil & Gas Operator | May 2013 |
| 460 | Powerline Energy Corporation | Arlington, TX 76015 | Oil & Gas Operator | Jul 2026 |
| 461 | PPP Petroleum LP | Dallas, TX 75201-1585 | Oil & Gas Operator | Apr 2026 |
| 462 | Premier Resources LTD | Denver, CO 80237 | Oil & Gas Operator | Jul 2002 |
| 463 | Prentice, Napier & Green, Inc. | Oklahoma City, OK 73142 | Oil & Gas Operator | May 2026 |
| 464 | Presidio Petroleum LLC | Canadian, TX 79014 | Oil & Gas Operator | Jul 2026 |
| 465 | Pri Producing Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2006 |
| 466 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Jul 2026 |
| 467 | Primary Natural Resources III LLC | Tulsa, OK 74136-6351 | Oil & Gas Operator | May 2026 |
| 468 | Primary Natural Resources Inc. | Tulsa, OK 74136-6351 | Oil & Gas Operator | Mar 2023 |
| 469 | Prime Energy Corp | Charleston, WV 25301-1707 | Oil & Gas Operator | Sep 2015 |
| 470 | Primexx Operating Corporation | Dallas, TX 75206 | Oil & Gas Operator | Mar 2024 |
| 471 | Princess Three Corporation | Henderson, TX 75653 | Oil & Gas Operator | Apr 2020 |
| 472 | Princess Three Operating, LLC | Henderson, TX 75653 | Oil & Gas Operator | Jul 2026 |
| 473 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 474 | Prospective Investment & Trading | Scottsdale, AZ 85261-4190 | Oil & Gas Operator | Jun 2016 |
| 475 | Protege Energy LLC | Tulsa, OK 74135 | Oil & Gas Operator | Jan 2018 |
| 476 | Proven Reserves Management, Inc. | Dallas, TX 75370 | Oil & Gas Operator | Apr 2026 |
| 477 | Qep Energy Company | Midland, TX 79701 | Oil & Gas Operator | Apr 2026 |
| 478 | Quantum Resources Management LLC | Houston, TX 77010 | Oil & Gas Operator | Apr 2026 |
| 479 | Questa Energy Corporation | Amarillo, TX 79159 | Oil & Gas Operator | Jul 2026 |
| 480 | Questar Explor & Prod Co | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2017 |
| 481 | R & A Moore, Inc. | Cleburne, TX 76033 | Oil & Gas Operator | Jul 2026 |
| 482 | R M S Oil & Gas | Amarillo, TX 79101-2445 | Oil & Gas Operator | Sep 1997 |
| 483 | Ram Asset Management Co | Oklahoma City, OK 73114 | Oil & Gas Operator | Mar 2015 |
| 484 | Ramco Oil & Gas Inc | Midland, TX 79701 | Oil & Gas Operator | Nov 2006 |
| 485 | Ramsey George H Estate | Ardmore, OK 73401-3644 | Oil & Gas Operator | Nov 2013 |
| 486 | Range Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2021 |
| 487 | Range Production Company, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2026 |
| 488 | Raven Resources LLC | Oklahoma City, OK 73172 | Oil & Gas Operator | Apr 2026 |
| 489 | Raydon Exploration, Inc. | Oklahoma City, OK 73118 | Oil & Gas Operator | Jul 2026 |
| 490 | RB Operating Company | Shawnee, OK 74802-1488 | Oil & Gas Operator | Apr 2015 |
| 491 | Reading & Bates Petroleum Co | Tulsa, OK 74136 | Oil & Gas Operator | Aug 2009 |
| 492 | Rebellion Energy LLC | Tulsa, OK 74135-6241 | Oil & Gas Operator | Jun 2022 |
| 493 | Red Bluff Resources Operating LLC | Oklahoma City, OK 73112-5468 | Oil & Gas Operator | Apr 2026 |
| 494 | Red Hawk Resources Inc | Edmond, OK 73003-3207 | Oil & Gas Operator | May 2026 |
| 495 | Red Rock Resources, L.L.C. | Wichita Falls, TX 76310 | Oil & Gas Operator | Apr 2026 |
| 496 | Redland Resources LLC | Oklahoma City, OK 73127 | Oil & Gas Operator | May 2026 |
| 497 | Redline Energy LLC | Dover, OK 73734 | Oil & Gas Operator | May 2026 |
| 498 | Redstone Oil & Gas Company | Dallas, TX 75225 | Oil & Gas Operator | Jan 2020 |
| 499 | Resource Oil And Gas, LLC | Oklahoma City, OK 73114 | Oil & Gas Operator | Jul 2026 |
| 500 | Revelation Resources | Cypress, TX 77410-2578 | Oil & Gas Operator | Apr 2026 |